WASHINGTON, March 19 (Xinhua) — Two astronauts from U.S. space shuttle Discovery’s seven-member crew performed the first of three planned spacewalks Thursday and successfully installed the International Space Station’s fourth and final set of solar array wings.

The NASA TV shows that Steven Swanson and Richard Arnold exited the space station’s Quest airlock at around 1:20 p.m. EDT (1720 GMT) to start the outing, which lasted about six hours and seven minutes. They struggled with some cable connections, but managed to hook everything up.

It’s Swanson’s third spacewalk of in his career and Arnold’s first.

According to NASA TV, Swanson and Arnold helped their colleagues — the robot arm operators inside the shuttle-space station complex cautiously move the S6 truss segment containing the folded-up wings to the starboard, or right side of the station.

“It wasn’t quite as smooth as we had hoped, but those guys did a great job,” astronaut Joseph Acaba told ground control teams.

The truss is a high-tech girder structure made up of 11 segments. It provides the backbone for the station, supporting the solar arrays, radiators and other equipment. To install the S6 truss segment, the station’s robot arm must extend its reach just about as far as it will go (about 57 feet or 17.4 meters), leaving it with very little room to maneuver. The S6 truss segment weighs a little more than 31,000 pounds or 14,061 kg. After S6 installation, the truss will be 335 feet (102 meters) long.

The space station’s six solar wings already are in place. The new ones will bring the number to eight, with four on each side.

Each solar array wing has two 115-foot-long (35 meters) arrays, for a total wing span of 240 feet (73 meters), including the equipment that connects the two wings and allows them to twist as they track the sun. Altogether, the station’s arrays can generate as much as 120 kilowatts of usable electricity — enough to provide about forty-two 2,800-square-foot (260 square meters) homes with power.

The new wings will bring the 10-year-old space station to full power, which is critical for boosting science research and allowing the crew to double to six.

Before concluding their spacewalk, Swanson and Arnold released and removed the locks and cinches holding down the wings, which will allow the wings to be unfurled on Friday.

Discovery was launched into space Sunday night. During its stay with the station, three spacewalks will be conducted by astronauts. If all goes well, it is scheduled to undock from the station on March 25, towards a planned March 27 landing at the Kennedy Space Center in Florida.